Pressure operated spray gun



' March 19, 1963 c. T. WALTER PRESSURE OPERATED SPRAY GUN Filed June 26, 1959 4 Sheets-Sheet 1 ATTORNEYS March 19, 1-963 0. -r. WALTER PRESSURE OPERATED SPRAY GUN 4 Sheets-Sheet 2 Filed June 26, 1959 INVENTOR CHARLES 72mm? Mum ATTORNEYS PRESSURE OPERATED SPRAY GUN Filed June 26. 1959 4 Sheets-Sheet 3 FIG 4 7 9 CHARLES Ham l 141115.? 8

BY I J W0, Fnfi M 4 {M b4 ATTORNEYS 1 OOO q -oo; q o0o' 2 I00 m; m i

HVVENTCE 20 March 19, 1963 c. -r. WALTER 3,081,947

PRESSURE OPERATED SPRAY GUN Filed June 26, 1959 4 Sheets-Sheet 4 INVENTOR 4 CHARLES 71mm? Wane-n ATTORNEY5 during a spraying operation.

United States Patent 3,081,947 r PRESSURE OPERATED SPRAY GUN Charles Taylor Walter, Lemout, Ill., assignor to Continental Can Company, Inc., New York, N.Y., a'corporation of New York Filed June 26, 1959, Ser. No. 823,065 20 Claims. (Cl. 239-246) The invention relates generally to the art of spraying utilizing a spray gun, and primarily seeks to provide a novel spray gun apparatus for spraying the interiors of can bodies and can ends. I

Inthe can manufacturing art, the interiors of certain can bodies, particularly aluminum can bodies, are provided with an enamel coating. In the conventional way of coating interiors of'can bodies, a stationary spray gun is, utilized and the can body being coated is rotated about the spray gun. The primary disadvantage of the conventional coating'process is that as the cans rotate about the spray gun, centrifugal force tends to redistribute'the coating material applied to the can bodyby the spray gun.

Another object of the invention is to provide a novel spray gun for use in the spraying-of a coating on the in-. terior of a can body, the spray gun being soconstructed that the spray gun may be rotated during a spraying operation and the spray gun having a spray orifice so positioned and directed that the side wall and end of a can will be coated by the relative telescoping movement between the can body and the spray gun while the spray gun is operating.

The normal spray gun utilizes air as a carrier for the liquid being sprayed. In View of this, it is necessary that a continuous uninterrupted passage be provided for the air-spray fluid mixture, orthat the air and the spray fluid be separately supplied tothe spray gun'where the two are mixed priorto the spraying: operation. In both of these arrangements, technical problems arise so as to make it not feasible to rotate the spray gun during the spraying operation. It is, therefore, another object of this invention to provide a spray gun which does not rely upon air as a carrier, but which is so constructed that the spray fluid per se may besupplie'd to the spray gun under a pressure so that the problem of providing a rotating connection for thesupply to the spray gun is greatly simplified and-a conventional type of rotating union may be utilized for this purpose so as to permit rotation of the spray gun Still another object of the invention is to provide a novelspray gun which includes a nozzle body having formed therein in axial alignment a cylinder and a valve seat, there being. mounted within the spray nozzle a combined piston an'd'needle valve member, the piston being normally spring urged towardsthe valve seat so as to seat the valve member on the valve seat, and there being provided an inlet passage into the nozzle body intermediate the piston. and the valve seat whereby when fluid under pressure is admitted into the nozzle body, it will,

movethe piston against. the resilient urging of the spring so asto move the needle valve member. out. of seating engagement with the valve seat. and thus effect the operation of the spray gun when spray fluidissupplied thereto at the operating pressure.

A further object of the invention is to provide a novel sprayr-gun and fluid supply system which includes a spray gun having a nozzle body in which there are formed a cylinder and a valve seat in axial alignment, the valve nozzle body" having positioned therein. a combined piston and needle valve member unit which is resiliently urged so that the needle valve' member: normally forms a seal with the valvese'at, the nozzle body being'so constructed that spray fluid is admitted thereto intermediate the piston and the valve seat so that when spray fluid; is; supplied to the nozzle body at the operating pressure for the spray gun, the piston, together with the needle valve member, is moved away from the valve seat to unseat the needle valve member, and the spray fluid supply system including a pump for supplying spray fluid at a pressure above the operating pressure of the spray gun, and there being provided a relief line in which there is mounted a relief valve, which valve when open, reduces the pressure of the spray fluid supplied to thespray gun so as to stop the operation of the spray gun.

Another object of theinvention is to provide a novel heating system by which enamel to be sprayed is maintained at a desired temperature at the spray nozzle.

A still further object of the invention isto provide a novel spray gun which is mounted for rotation, the spray gun including a centrally locatedspray nozzle assembly including a spray orifice offset from the center of rotation, and an outer spray nozzle assembly which includes an orifice greatly spaced from thecenter of rotation of the spray gun, the last mentioned spray orifice being directed in a line generally parallel to the axis of rotation whereby the centralnozzle assembly may spraythe wall and end of a can body and the outer nozzle assembly may spray into a valley formed between the can body walland end.

' Another object of the invention is to provide a novel spray gun which includes a plurality of spray nozzles, each of the spray nozzles being actuated by the supplying of spray fluid thereto at a predetermined pressure, the operating pressure of oneof the spray nozzles being higher than the operating pressure of the other of the spray nozzles and the spraynozzles receivingspray fluid from a common source whereby by varying the pressure of. the supply sources, the spray nozzles may be selectively actuated.

Still another object of the invention is to provide a i 7 novel spray gun for'spraying the interior of can bodies,

of a rotating union, the spray gun having a spray nozzle which includes a pair of orifices disposed generally transverse to the axis of rotation whereby the spray gun is particularly adapted to spraying can bodies having side seams, and" the orifices are sorelated to the can body whereby the fluid is directed into the opening formed between tlie can body side wall and the side seam hook as-well as onto the rear sloping surface of the side seam.

Yet another object of the invention is to provide a novel spray gun for spraying the interiors of can bodies and the like, the spray gun being mounted on a rotating union and having a drive connection with a drive source whereby the spray gun may be rotated during the spraying operation therewith, the spray gun includinga central nozzle'assembly and a pair of outer nozzleassemblies, the outer nozzle assemblies being disposed in generally diametrically opposite relation with respect to each other, and the entire spray gun being balanced for rotationat a high speed. With the above, and other objects in view that will hereinafter appear, the nature of the invention will be I more clearly understood byreference to thefollowing detailed' description, the appended claims, and the several views illustrated in the accompanying drawings.

'In the drawings: p FIGURE 1 is a schematic view showing a single nozzle form of rotating'spray gun and the spray fluid supply system for the spray gun. 7

FIGURE 2- is a schematic 'viewshowinga multiple nozzle spray gunof the type which is mountedforrotation and wherein the individual nozzles are operated at ditierent operating pressures, and a spray fluid supply system for supplying spray fluid to the spray gun at the desired operating pressures.

FIGURE 3 is an enlarged fragmentary elevational view of the spray gun of FIGURE 1 and shows the relationship of the spray gun with respect to a can body during a spraying operation.

FIGURE 4 is an enlarged longitudinal sectional view taken through the center of the spray gun of FIGURE 1 and shows the specific internal construction thereof and the connection between the spray gun and the rotating union.

FIGURE 5 is an enlarged transverse sectional view taken along the line 5-5 of FIGURE 4 and shows the details of the spray nozzle of the spray gun in the vicinity of the needle valve thereof.

FIGURE 6 is an enlarged fragmentary sectional view taken along the line 6-6 of FIGURE 4 and shows the details of the nozzle base in the vicinity of the connection to the rotating union.

FIGURE 7 is an enlarged fragmentary longitudinal sectional view taken through the spray gun of FIGURE 2 and shows the specific details of construction hereof and the relationship of the outer nozzle with respect to the centrally located nozzle.

FIGURE 8 is an enlarged fragmentary sectional view taken along the line '88 of FIGURE 7 and shows further the details of the spray gun of FIGURE 2.

FIGURE 9 is an enlarged fragmentary top perspective view of still another form of spray gun which includes a central nozzle and two outer nozzles.

FIGURE 10 is a rotated enlarged fragmentary perspective view of a modified form of spray nozzle.

FIGURE 11 is an end view of a can body of the type having a side seam, and shows the spray nozzle of FIG- URE 10 in operation spraying the interior of the can body.

A simple form of the spray gun and spray fluid supply system is illustrated in FIGURE 1. The spray gun is generally referred to by the numeral 5 and the spray fluid supply system is generally referred to by the nu Ineral 6. The spray gun 5 is coupled to the spray fluid supply system 6 for rotation by means of a rotating union 7. The union 7 is a Model 1105 Deublin union, manufactured by the Deublin Company of Glenview, Illinois.

Reference is now had to FIGURE 4 wherein there are illustrated the details of the spray gun 5 and the upper end of the rotating union 7. The rotating union 7 includes a housing 8 which has mounted in the upper end thereof a ball bearing 9 which aids in the supporting of a rotor 10 for rotation. The rotor 10 has a nut portion 11 to facilitate the holding thereof, and the upper end of the rotor 10 terminates in a reduced externally threaded portion 12. The rotor 10 also has a bore 13 which opens through the upper end thereof. The rotating union 7 also includes an outlet pipe 14 which extends through the bore 13 and projectsabove the upper end of the rotor 10. A strainer 15 is coupled to the upper end of the outlet pipe 14 for receiving spray fiuid therefrom.

The spray gun 5 includes a nozzle base 16 which is generally tubular and which has a centrally located relatively large diameter bore 17 in the lower part thereof. The bore 17 terminates at the lower end thereof in an enlarged internally threaded bore 18 in which the reduced externally threaded portion 12 of the rotor 10 is threadedly engaged. A gasket 20 is disposed intermediate the rotor 10 and the nozzle base 16 to form a seal therebetween. A drive pulley 21 is secured to the lower end of the nozzle base 16 to facilitate the rotation of the spray gun 5.

The upper part of the nozzle base '16 is provided with a bore 22 which is offset from the bore 17. The bore 22 has seated in the outer part thereof a nozzle body generally referred to by the numeral 23. The nozzle body 23 may have a press fit with the nozzle base 16 or may be secured in the bore 22 in any other desired manner.

The bore 17 receives spray fluid from the outlet pipe 14 through the strainer 15. The upper end of the bore 17 is generally funnel-shaped, as at 24, and terminated in a reduced cross-sectional bore 25. Extending transversely of the nozzle base 16 and intersecting the bore 25 is a bore 26 which has one end thereof plugged by a plug 27. The bore 26 intersects a longitudinal bore 28 which extends the full length of the nozzle base 16 from the bore 26 and which has the upper end thereof plugged by a plug 29.

The nozzle body 23 has formed in the lower end thereof a cylinder 30 which terminates at the upper end thereof in a bore 31. The upper end of the bore 31 terminates at a valve seat 32 which, in turn, terminates in a bore 33. A transverse bore 34 in the upper end of the nozzle body 23 above the nozzle base 16 intersects the upper end of the bore 33. One end of the bore 34 is closed by a plug 35, and the opposite end of the bore 34 intersects the longitudinal bore 36. The upper end of the nozzle body 23 is cut on a bevel as at 37 and has a bore opening therethrough. A spray tip 38 is seated in the bore.

The lower end of the cylinder 30 is open and opens into the bore 22 in the nozzle base 16. Positioned within the cylinder 30 is a piston 40 of a piston and needle valve member unit generally referred to by the numeral 41. Connected to the upper end of the piston 40 is an elongated needle valve member 42 which extends through the bore 31 and which has an end portion 43 cooperable with the valve seat 32 to form a seal therewith. The lower part of the piston 40 i provided with an O-ring 44 which forms a seal with the wall of the cylinder 30 and prevents the escape of spray fluid downwardly past the piston 40. The lower end of the piston 40 terminates in an enlarged washerlike member 45 which is disposed in the upper part of the bore 22.

Seated in the bottom of the bore 22 is a base 46 of an elongated stop member 47. The stop member 47 is aligned with the piston 40 and engages the enlarged end portion 45 of the piston 40 to limit the movement of the needle valve member 42 away from the valve seat 32. A spring 48 surrounds the stop member 47 and is seated on the base 46. The upper end of the spring 48 engages the enlarged end portion 45 of the piston 40 and urges the piston 40 and the needle valve member 42 upwardly so that under normal conditions, the needle valve member 42 has the end portion 45 thereof disposed is seating sealed engagement with the valve seat 32.

The upper part of the bore 28 has opening in thereto a flow passage 49. The flow passage 49, in turn, opens into an annular passage 50 surrounding an intermediate portion of the nozzle body 23. Extending between the annular passage 5i) and the bore 31 is an inlet passage 51. Thus, the spray fluid is supplied to the nozzle body 23 intermediate the piston 40 and the valve seat 32. When the spray fluid is at the operating pressure for the spray gun 5, the pressure exerted on the piston 40 by the spray fluid will result in the downward movement of the piston and needle valve member unit 41 against the upward resilient urging of the spring 48, with the result that the needle valve member 42 is unseated from the valve seat 32 and the piston 40* moves downwardly into engagement with the stop member 47. The spray fluid 'now passes into the bore 33, the bore 34, and the bore 36, and finally out through the spray tip 38. It is desirable to limit the movement of the piston and needle fluid supply system '6 includes a reservoir '52 in which a drawn therefrom by the pump 55. An outlet pipe 56 is "connected to the pump 55 and the opposite end of the outletpipe 56 is connected to a cross-pipe 57 in which there are positioned on opposite sides of the outlet pipe 56 a pair of flow control valves 58 and 59. A return pipe 60 .is coupled to the flow control valve 59. On the other hand, fa spray fluid supply line or pipe .61 is coupled to :the flow control valve 58. A gauge 62 is coupled to'the outlet pipe 56 for indicating the output pressure of the pump 55. An accumulator 63is also connected to the outlet .pipe 56. The accumulator 63 is of'the type having air pressure in the upper end thereof, as at 64, to cushion sudden pressure changes within the outlet .pipe 56.

the fitting 65. The return pipe .66 is connected to afreturn valve generally referred to by the numeral 67. The return valve 67 includes a housing 68 which has formed therein a valve seat 69 against which a ball type valve member 70 bears to seal off the entrance to the housing 68. The ball valve member 70 has connected thereto a rod 71 which extends through the housing 701and which has connected on'the opposite end thereof afollower 72.

'The follower 72 engages a cam 73 which is mounted on .a shaft .74. The shaft 74 will be driven in any desired manner in timed relation to a mechanism .(not shown) forpositioning a cam body with respect to the spray gun 5. A return line 75 extends from the return valve 67 to the reservoir52.

In order to facilitate the rotation of the'spray' gun 5, an electric motor .or other type of driveunit 76 is provided. The electric motor 76 is provided with a drive :pulley 77 which is aligned with the pulley-21. Entrained over the .pulleys 21 and 77 is a drive belt 78. At this time, it is pointed out that the speed of rotation of the electric motor 76 and :the-drive ratio between the drive pulley 77 and the pulley 21 should be such that the spray gun may be rotated at speeds of 3,000 rpm. and above. It is also pointed out at thistime that it is contemplated utilizing the spray gun 5 in multiples in a turret type operation andthat a single-electric-motor 76 may drive a number of spray guns 5 which are mounted in the turret assembly.

Operation In the operation of the simplified form of the invention illustrated in FIGURES -l, 3, 4, 5 and 6, the desired spray fluid 53 is supplied to the reservoir 52. The pump 55 is then driven in any desired manner with the result that the sprayfluid 53 is forced throug'hthe outlet pipe 56 under pressure from the pump 55. The spray fluid through the return pipe 60. Thus,. by proportioning the flowot spray fluid throughthe flow control valves 58 and 59, the desired flow of sprayfluid to the spray gun 5 may be obtained.

When the spray gun 5*is-notoper-ating, thereturn valve 67 is in an open position due to the positioning oi the nozzle body 82, when forming a part of the spray gun 5,

rotates within the can body 89, spray fluid from the spray.

. "6 cam 73. At this time, the pressure of the spray fluid Withinthespray gun 5 is insufficient to unseat the needle valve member 42 from the valve seat 32. When the cam 73 is rotated to the position illustrated in FIGURE 1,

flow ofthe spray fluid from the rotating union 7 through the return'line is discontinued with the result that the full operating pressure of the spray fluid supply system -6 may be directed to thespray gun 5.

The operation of the cam 73 and the rotation of the camshaft 74 .is in timed relation to the positioning of a 'canbody, such as the can body 80, with respect to the spray gun 5. As the nozzle body 23 of the spray gun 5 begins to enter the can body 80, the cam 73- will close the return valve 67 with the result that the spray fluid will spray a coating on the inner surface of the wall of the can body 80. As the telescoping movement of the can body 80 over the spray gun 5 continues, the entire wall of the can body 80 is sprayed. When the can body 80 reaches its maximum position of telescoping relation with respect to the spray gun 5, the spray fluid 53 being sprayed from the spray gun 5 will strike the can end and apply the desired coating to the can end, as is best shown in FIGURE 3. The cam 73 may be so configurated so as to open the return valve 67 at this time, or a second coating may be applied to the wall of the can body 80 as the spray gun 5 moves out of telescopedrelation with respect to the can body 8%. In any-event, the spraying operation will discontinue as the spray gun 5 moves-out ofthe can body 80.

It is not the intention of this invention to restrict the use of the spray gun to the spraying of interior of can bodies or the manner in whicht-he spray gun 5 may be positioned withrespect tothe can bodies 80. It will be readily apparent that various mechanisms may be devised to accomplish this result.

Reference is now had to FIGURES l0 and 11, wherein there is illustrated a modified form of nozzle body 82 for the spray gun 5. The nozzle body 82 differs from the nozzle body 23 in that in lieu of the bevelled end of the nozzle body 23, the nozzle body 82 hasa transverse head 83. The head 83 is generally rectangular in outline-and has seated therein a pair of spray tips 84 and 85 which extend generally transversely to-the axis of rotation of the spray gun of which the spray nozzle 82 is apart. It is to be notedthat the axis of the spray tip 84 is disposed nor mal to aplane passing'through the center of the head'83 and the'center of the nozzle body 82, Whereas the axis of the spray tip 8'51is disposed at a slight angle to such a plane. The axes of the spray tips 34 and 85 converge, as is best shown in FIGURE 11.

The spray tips 84 and 85 are communicated with the interior of the nozzle body 82 by means of suitable passages 6 and 87, respectively. The passages 86 and 87 are, in turn, connected toa'passage 88 which corresponds to the bore 33.

The nozzle body 82 is utilized in conjunction with the spray gun 5 when an endless can body 89 having a side seam 9%} is to be sprayed. It is to be noted that the direction of rotation'of the nozzle body 82 is in the direction which the axis of the spray tip 35 slopes. Thus, as the tip 35 is directed into the opening formed between the hook on the side seam 9t} and the can body side wall. At

the same time, the spray fluid from the spray tip' 84, as the nozzle body 82 rotates, suitably coats the sloping left side of the side seam 90, as viewed in FIGURE 11.

Referenceis now had to FIGURE 2 wherein there is illustrated another form of the invention which includes a spray gun generally referred to by the numeral 91 and a spray fluid supply systemgenerally referred to by the numeral 92. The spray gun 91 is connected to the spray fluid supply system 92 by means of a rotating union 93 which will be constructed identically to the union 7. Also, the spray gun 91 is rotated by means of an electric motor 7 94 having a drive pulley 95 aligned with a pulley 96 of the spray gun 91 and drivingly connected thereto by means of a drive belt 97.

The details of the spray gun 91 are best illustrated in FIGURES 7 and 8, and the spray gun 91 includes a central nozzle assembly in the form of the spray gun and an outer nozzle assembly generally referred to by the numeral 99. In the spray gum 91, the plug 27 which normally closes the bore 28 in the nozzle base 16 is removed to permit the flow of spray fluid to the nozzle assembly 99.

The outer nozzle assembly 99 includes a circular crosssectional nozzle body 102 which has a generally central bore 103 receiving the nozzle base 16. The bore 103 terminates at its upper end in an oflfset and reduced bore 104 which receives the upper part of the nozzle body 23. The nozzle body 102 is retained on the nozzle base 16 by means of a setscrew 105 which is best illustrated in FIG- URE 8.

The nozzle body 102 is recessed adjacent the lower end thereof surrounding the bore 103 to form an annular passage 106. Disposed above and below the annular passage 106 are annular grooves 107 and 108 in which there are seated O-rings 109. Thus, a seal is formed between the nozzle body 102 and the nozzle base 16. It is to be noted that the annular passage 106 is vertically aligned with the bore 26 so that it may receive spray fluid from the bore 26.

The nozzle body 102 is also provided with an internally threaded bore 110 which is offset from the bore 103 and opens through the lower end of the nozzle body 102. The internally threaded bore 110 terminates at its upper end in a smooth wall bore 111 which, in turn, terminates at its upper end in a cylinder 112. The cylinder 112 has an inverted funnel-shaped upper portion 113 which terminates in a bore 114. At the upper end of the bore 114 is a valve seat 115 which surrounds the lower end of a bore 116. It is to be noted that the valve seat 115 and the bore 116 are formed in an upwardly projecting part 117 of the nozzle body 102, the general cross-section of the part 117 being best shown in FIGURE 8.

The lower end of the internally threaded bore 110 is closed by means of an externally threaded plug 118. The plug 118 has an internally threaded bore 119 therethrough. Threadedly engaged in the bore 119 and passing therethrough is an elongated stop member 120.

Positioned within the cylinder and the bore 114 is a piston and needle valve member unit generally referred to by the numeral 121. This unit is identical to the piston and needle valve member unit 41 and includes a piston 122 and a needle valve member 123. The piston 122 is seated in the cylinder 112 and the needle valve member 123 has an end portion 124 which cooperates with the valve seat 115 to close the bore 116. The piston 112 projects down into the bore 111 and terminates at its lower end in a washerlike portion 125. Disposed above the washerlike portion 125 is an O-ring 126 which engages the wall of the cylinder 112 and prevents the escape of spray fluid past the piston 122 and into the bore 111.

Disposed within the bore 111 and the upper portion of the bore 110 is a spring 127. The spring 127 is seated on the plug 118 and bears against the underside of the washerlike portion 125 so as to urge the needle valve member 123 into engagement with the valve seat 115. It is intended that the outer nozzle assembly 99 operate at a higher pressure than the central nozzle assembly 5. This is accomplished by adjusting the tension of the spring 127 through the adjustment of the position of the plug 118 by threading the plug 118 into or out of the internally threaded bore 110. The plug 118 is retained in an adjusted position in the bore 110 by means of a setscrew 128 (FIGURE 8). When the needle valve member 123 is engaged with the valve seat 115, the piston 122 is spaced above the upper end of the stop member 120. The position of the stop member 120 is adjusted by threading it into or out of the plug 118. The stop member 120 is retained in an adjusted position by means of a lock nut 130 which is threadedly engaged on the lower end of the stop member and abuts the lower end of the plug 118.

The bore 114 is communicated with the annular passage 106 by a plurality of bores which, are illustrated in FIGURES 7 and 8. A horizontal bore 131 is drilled from the exterior of the nozzle body 102 into the annular passage 106. The outer part of the bore 131 is plugged by means of a plug 132. A vertical bore 133 is drilled through the bottom of the nozzle body 102 parallel to the axis of the nozzle body 101 and crossing the horizontal bore 131. The lower end of the vertical bore 133 is plugged by means of a plug 134. An upper horizontal bore 135 is drilled through the nozzle body 102 from the exterior thereof through the center of the bore 114 and into the upper end of the vertical bore 133. The outer part of the horizontal bore 135 is closed by a plug 136. Thus, spray fluid is supplied to the outer nozzle assembly 99 into the bore 114 intermediate the piston 122 and the valve seat 115. When spray fluid is supplied to the bore 114 at a pressure suflicient to unseat the needle valve member 123 and overcome the tension of the spring 127, firay fluid under pressure will be admitted to the bore In FIGURE 7, the upper end of the nozzle body 101 has been illustrated as being bevelled and sloping downwardly and to the right. A bore opens through the upper end of the nozzle body 101 and a spray tip 137 is seated in the bore with its axis generally normal to the upper end of the nozzle body 11. The spray tip 137 thus directs spray fluid upwardly and to the right so that spray fluid from the spray tip 137 will coat both the interior surface of the wall of the can body and the can end when the spray gun 91 is rotated.

The upper end of the upwardly projecting part 117 of the nozzle body 102 has the left hand portion thereof (FIGURE 7) cut away toslope downwardly and to the left, as at 138. Extending downwardly from the upwardly sloping face of the part 117 and normal thereto is a bore 139 which intersects the bore 116 at the upper end thereof. The bore 139 has an upper internally threaded end portion 140 in which there is threadedly engaged a spray tip 141 having a bore 142 therethrough. "The spray tip 141 terminates at the upper end thereof 111 a spray orifice 143, the axis of which is disposed parallel to the axis of rotation of the spray gun 91. Thus, the spray fluid from the spray orifice 143 defines an annular pattern.

The spray gun 91 is primarily intended for use in the spraying of the interior of a can body, such as the can body 144. .The can body 144 is of the drawn type, and includes a wall 145 and an end 146, which are integrally formed. In the formation of the can body 144, a relatively deep recess 147 is formed at the intersection of the wall 145 and the end 146. The central nozzle assembly 5 is intended to spray the necessary spray fluid on the wall 145 and the can end 146 to provide the coating. The outer nozzle assembly 99 is intended to coat only the intersection between the wall 145 and the end 146, and more particularly in the recess 147.

Reference is again made to FIGURE 2 wherein there are illustrated the details of the spray fluid supply system 92. The spray fluid supply system 92 includes a reservoir 148 in which the desired spray fluid 149 is stored. An inlet pipe 150 is connected to the reservoir 14 8 for receiving spray fluid 149 therefrom. The inlet pipe 15-0 is connected to a gear type pump 151 which discharges the spray fluid 149 under pressure to an outlet pipe 152. A cross-pipe 153 is connected to the end of the outlet pipe 152. The cross-pipe 153 has connected at opposite ends thereof flow control valves 154 and 155. A return pipe 156 is connected to the flow control valve and empties into the reservoir 148 for returning spray fluid to the reservoir. A spray fluid supply pipe 157 is connected to the flow control valve 154 and to a fitting 158 of the rotating union 93.

The gear type pump 151 has a constant output, and the pressure in the outlet pipe .152 may be controlled by controlling the flow of spray fluid-through "the flow control valves 1'54 "and 155. Thus, the pressure of the spray fluid entering into the 'union 93 is regulated. The Epressureof the spray'fluid'is visually determined by means ofa'g'auge 160 which is coupledto the outlet pipe 15 2. The outlet-pipe 1'52 is also 'providedwith an accumulator 161 for 'the purpose of preventing any sudden change inpressure due tothe stopping or starting of'the spraying "operation.

The-union 93, like the union 7, isof therecirc'ulating type with the result that the fitting "158 has connected thereto not only the spray fluid supply pipe 157, but also areturnfp'ip'e 16 2; "The-return pipe *162Lis-connected to a return valve generally referred to by the numeral 163.

The return valve includes a housing 164 in which there isformed a valve "seat 165. Cooperating with lthe *valv'e seat-165 is'a ball'type'valve member 166 for closing the entrance to the "housing 164.

The balbv-alve-member 1665s operated .by means of a'rodI1-67 whichhas connected to theopposite en'd thereof a follower 168 which is disposed *exteriorly of the housing 164. The follower "168 is engaged with a cam *169which is,"in turn, carried by a camsha'ft 170.

Coupledf-to thereturn pipe162is a pipe 171 in which fthere is mounted a fiowcontr'ol valve 172. 'The pipe "171 i sals'oco'nnected to a second return valve -173 which is i'denticail with the'return valve -163 and the operation of which is controlled "by means of a cam 174 carried "b-y'acamshaft 175. Connected to the return valve 173 'is "a return line, the opposite end of which opens into "the reservoir- "-148. The-return line --is referred to by the numeral 176 and has coupled thereto a return line 177 ifr-om-thereturnwalve 163. "The pipe -'171 and the return ilin'e 1*76 combine 'to "define a lay-pass line.

Operation 'Inorder to unde'rstandthe loperation of the form-of 'theinvention illustrated inFIGURES 2, 7 and :8, it is "necessary to first understand Lthatthe camshafts 170 and 175 are-driven -in timed relation to themechanism which will position the can -body 144 relative to the spray gun '9-1. lBys o driving the camshafts 170 and '175, the return valves 163 and 173 will beope'nedin 'the'proper timed relation.

.The'pump 151 supplies spray .fluid 148 at a desired pressure tothe' fitting'15'8. When atcan body is not positioned with respect T the :spray gun 91 for a spraying operation, the return' valves 163 and 173, will be'opened, 'with the result 'thatiinsufiicient pressure will-be applied on thepistons of the nozzle assemblies Sand 99 to unseat the needle valve'rnem-bers of these nozzle assemblies. However, as the can :body 144 begins to telescope over the spray gun 91, the return valve 163 is closed, with the result that the pressure of the spray fluid supplied to the spray gun 91*will-be raisedto that necessary'for the operation of the central nozzle. assembly 5. As the can b'ody1'44is lowered over the spray gun 91-or the spray gun 91 is moved upiinto the, can :body 144, the central nozzle assembly '5 will function so as to; coat the 'can -oody wall on the interior surface thereof. -:As-the can body 14-4 approaches the positionillustrated "in FIGURE 2,

thereturn valve 173 will also be closed withthe result thati-thetpressure of the'spray fluid delivered to the spray wigll1191 will be additionally increased so as to operate the outer nozzle assembly 99. At this time, spray fluid will also -.be sprayed from thevspray orifice 14-3 :s oas to coat the interior of the can body 144 at the intersectionnbetween the wall 145 and the end 146. As the ean body 144. approaches the position illustrated FIGURE -2, the spray :fluid spraying from the spray .tip :lfa-Twillbeidirected.against the-end 146 so as to'als'o coat the-end of the canbody 144.

withdraw from the spray gun 91, the return valve 173 will be opened so as to discontinue the operation of the outer nozzle assembly 99'. Ifdesired, the return valve 163 may-also be opened at this time so as to discontinue the operation of the central nozzle assembly 5. On the other hand, the central nozzle assembly 5 may continueto fun'ction until the can body 144 has been completely removed from the spray .gun 91 so that a seeondcoat may be applied-to the wall of the can body.

"Reference is now had to FIGURE 9 wherein there'are illustrated the details of a modified 'form of spray gun, generally referred to by the numeral 178. The spray gun 178 inclu.des a central nozzle assembly 179 and a pairof outer nozzle assemblies generally referred to by the numerals 180 and 181 The outer nozzle-assemblies 180 and 181 have acommon mounting block or nozzle body 182 which is carried by the central nozzle assem- 'bly 1-79, as is the nozzle body 102. 'The nozzle body 182 differs 'fromthe nozzle body 102 primarily in that it is tips 184 are "identical with the spray tip 141. Although it has not been so-illustrated, the nozzle'body 182 will contain a valve'assembly foreachof'the nozzle assemblies 180 and 181'which is-identical to the valve assembly for the nozzle assembly '99. 'The valve assemblies for the outer nozzle assemblies 180 and"181 rnay be adjustedto operate simultaneously.

It is to be'n'otedthat the-nozzle assemblies180 and 181 are mounted-in diametrically opposite relation onopposite sides of the central nozzle assembly 179. While in the spray gun 91, the nozzle 'assembly'S faced away from the nozzle assembly 99, in view of the fact that two nozzle assemblies-180 and lslare provided, the nozzle '179 cannot so face. It is necessary that the nozzle assembly 179 .lface in a direction -normal to a line extending between the centers of the nozzle assemblies 180 and 181. The central nozzle assembly 179 includes a "spray .tip 186 whichopens upwardly and outwardly between the pro- -jectin-g .parts 183. The operation and function of the spray gun 178 will be identical to that ofthe spray gun '91, and further description is believedto be unnecessary.

It has been found that a superior coating is obtained through enamel spraying by maintaining the temperature of the enamel at the spray nozzle at an optimum tem perature duringthe spraying operation. The optimum temperaturewill, of course, vary depending upon the particular enamel being sprayed and other spray coating As an example of an enamel temperature, ap proximately 140 degrees F. at the spray nozzle has been "found to give very satisfactory results for a particular installation.

Referring once againv to FIGURE 1 in particular, it will be seen that an electricthermostatically controlled heating element 187 is-poistioned within the reservoir 52 below 'the'surface of the spray 'fiuid'53 for directlylheating the spray-fluid. Atemperature sensing element 188 is also mountedon the reservoir52 and has the pickup ;end thereof disposed within'the :spray .fiuid 53. The temperature sensingelement 188 is'suitab'ly electrically coupled with the heating element'137 to controlthe operation thereof and maintain the temperature :of the spray fluid within thedesired heat range. The spray fluid 149 of the V reservoir 148 may be similarly heated.

The shape 9f the cams I69 and 174 may be varied as V is desired. However, as the'canbody 144 begins to The heating of the spray fluid 53, normally enamel,

withi'nthe reservoir 52 and the continuous circulation of the spray fiuid through the spray gun 5 or similar spray guns during the off periods of the spray nozzlethereof provides a novelheating system for the spray gun. Sufiicient heated enamel or other spray fluid is circulated through the spray gun to'the area of 'the'spray nozzle thereof toheat the spray nozzle by conduction, thus maintaining all areas of heat transfer within the spray gun at a temperature substantially equal to the temperature of the spray fluid and minimizing the heat transfer. The spray gun and similar spray guns represent relatively large masses into which a large amount of heat may be transferred during a relatively short spraying cycle. When the heated enamel is supplied to a much cooler spray nozzle in the normal manner, the mass of the enamel being small as compared to the mass of the spray gun, the enamel loses much of its heat to the spray gun. In order to compensate for the heat losses at the spray nozzle under these conditions, it is necessary that the temperature of the spray fluid Within the reservoir be heated to a somewhat higher temperature than that desired at the spray nozzle.

While several forms of the invention have been shown for purposes of illustration, it is to be clearly understood that other changes in the details of construction and arrangement of parts may be made without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed as new:

1. In a pressure operated spray gun, a nozzle assembly comprising a nozzle body, a nozzle orifice in one end of said nozzle body, said nozzle body having a cylinder and a needle valve seat .disposed in axial alignment and in communication with said nozzle orifice, a piston and needle valve member unit mounted in said nozzle body and cooperating with said cylinder and said needle valve seat, respectively, for controlling the flow of spray fluid to said nozzle orifice, a resilient member seated in said cylinder and bearing against said piston to normally urge said needle valve member into engagement with said needle valve seat, said nozzle body having a spray fluid inlet passage opening into said cylinder intermediate said piston and said needle valve seat, whereby said needle valve member is unseated by the pressure of spray fluid on said piston when the spray fluid pressure is at the operating pressure of the nozzle assembly to supply spray fluid to said nozzle orifice, means connected to said nozzle body for rotating said nozzle assembly, and said nozzle orifice having an axis disposed in angular relation to the axis of rotation and offset relative thereto to provide a moving spray pattern.

2. The nozzle assembly of claim 1 together with a stop member aligned with said piston and disposed remote from said valve seat for engagement by said piston to limit the opening movement of said needle valve member relative to said valve seat, whereby the volume of spray fluid pumped back into the spray fluid inlet passage by said piston when said need-1e valve member goes from unseated to seated position will be held to a controlled minimum.

3. In a pressure operated spray gun, a nozzle assembly, said nozzle assembly comprising a nozzle base having an open end, a nozzle body in said nozzle base open end and projecting therefrom, a nozzle orifice in one end of said nozzle body, said nozzle body having a cylinder and a needle valve seat disposed in axial alignment and in communication with said nozzle orifice, a piston and needle valve member unit mounted in said nozzle body and cooperating with said cylinder and said needle valve seat, respectively, for controlling the flow of spray fluid to said nozzle orifice, a resilient member seated in said cylinder and bearing against said piston to normally urge said needle valve member into engagement with said needle valve seat, said nozzle body having a spray fluid inlet passage opening into said cylinder intermediate said piston and said needle valve seat, and said nozzle base having a spray fluid supply passage opening into said spray fluid inlet opening, whereby said needle valve memher is unseated by the pressure of spray fluid on said piston when the spray fluid pressure is at the operating pressure of the nozzle assembly to supply spray fluid to said nozzle Orifice, a support for said nozzle base in the 12 form of a rotating union, a drive pulley secured to said nozzle base for rotating said nozzle assembly during a spraying operation, and said nozzle orifice having an axis disposed in offset relation to the axis of rotation to provide a moving spray pattern.

4. The nozzle assembly of claim 3 together with a stop member supported by said nozzle base remote from said valve seat and aligned with said piston for engagement by said piston to limit the opening movement of said needle valve member relative to said valve seat, whereby the volume of spray fluid pumped back into the spray fluid inlet passage by said piston when said needle valve member goes from unseated to seated position will be held to a controlled minimum.

5. A spray gun and spray fluid system assembly, said spray gun including a spray nozzle having valve means openable in response to the directing of spray fluid at an operating pressure into said spray nozzle, a spray fluid reservoir, a pump disposed remote from said spray gun connected to said spray fluid reservoir for constantly supplying spray fluid at a pressure in excess of the operating pressure of said spray gun, a spray fluid supply line connecting said spray gun to said pump, a by-pass line extending between said spray fluid supply line and said reservoir, other valve means in said spray fluid supply line and said by-pass line controlling the pressure of spray fluid supplied to said spray gun, a return line from said spray gun to said spray fluid reservoir, a return valve in said return line, and means for operating said return valve, whereby operation of said spray gun is controlled.

6. The assembly of claim 5 wherein said spray fluid system also includes an accumulator connected to said spray fluid supply line intermediate said pump and said by-pass line.

7. A spray gun and spray fluid system assembly, said spray gun including a spray nozzle assembly comprising a nozzle body, said nozzle body having a cylinder and a needle valve seat disposed in axial alignment, a piston and needle valve member unit mounted in said nozzle body and cooperating with said cylinder and said needle valve seat, respectively, a resilient member seated in said cylinder and bearing against said piston to normally urge said needle valve member into engagement with said needle valve seat, said nozzle body having a spray fluid inlet passage opening into said cylinder intermediate said piston and said needle valve seat, whereby said needle valve member is unseated by the pressure of spray fluid on said piston when the spray fluid pressure is at the operating pressure of the nozzle assembly, means remote from said spray gun for constantly supplying spray fluid at said spray gun operating pressure to said spray gun, said means including a spray fluid supply and a return line connected to said spray fluid supply, and a return valve controlling the flow of spray fluid through said return line, whereby operation of said spray gun is controlled.

8. The system of claim 7 wherein said nozzle body includes a spray orifice offset from said cylinder axis and opening generally endwise of said nozzle body towards and at an angle to said cylinder axis.

9. The system of claim 7 wherein said nozzle body includes a spray orifice ofliset from said cylinder axis and opening from said nozzle body generally transverse to said cylinder axis.

10. The system of claim 7 wherein said nozzle body has a pair of spray orifices oflset from said cylinder axis on opposite sides thereof and opening from said nozzle body generally transverse to said cylinder axis.

11. In a pressure operated spray gun, a pair of separate nozzle assemblies, each of said nozzle assemblies comprising a nozzle body, said nozzle body having a cylinder and a needle valve seat disposed in axial alignment, a piston and needle valve member unit mounted in said nozzle body and cooperating with said cylinder and said needle valve seat, respectively, a resilient member seated in said cylinder and bearing against said piston to normally urge said needle valve member into engagement with said needle valve seat, said nozzle body having a spray fluid inlet passage opening said cylinder intermediate said piston and said needle valve seat, whereby said needle valve member is unseated by pressure of spray fluid on said piston, means connecting said nozzle assemblies to a common pressurized spray fluid source, and the pressure required to overcome the force of said resilient member of one of said spray nozzles being greater than the pressure required to overcome the force of the resilient member of the other of said spray nozzles whereby said other spray nozzle and both of said spray nozzles may be selectively operated.

12. The nozzle assemblies of claim 11 wherein said nozzle body of one of said nozzle assemblies is supported from the other of said nozzle assemblies.

13. The nozzle assemblies of claim 11 together with means for rotation of said nozzle assemblies generally about the axis of one of said nozzle assemblies, the other of said nozzle assemblies being offset from said axis, whereby the spray pattern from one of said spray nozzles is generally circular in outline and the spray pattern from the other of saidspray nozzles is generally annular in outline.

14. The nozzle assemblies of claim 13 wherein the nozzle body of one of said nozzle assemblies is circular and is telescoped over the other of said nozzle assemblies.

15. The nozzle assemblies of claim 13 wherein said nozzle assemblies are generally dynamically balanced.

16. A rota-ting spray gun for spraying the interior of cans, said spray gun having an axis of rotation and comprising a central nozzle and an outer nozzle, said central nozzle having a spray orifice offset from said axis of rotation and opening generally endwise from said central nozzle towards and at an angle to said axis of rotation for spraying the interior of a can body and a can end, and said outer nozzle having a spray orifice offset from said axis of rotation a considerable distance and opening generally parallel to said axis of rotation for spraying the interior of a can at the intersection between the can body and the can end.

17. The spray gun of claim 16 together. with control means for first operating said central nozzle independently of said outer nozzle and then operating said outer nozzle together with said central nozzle.

18. A spray gun and spray fluid system assembly, said spray gun including a pair of spray nozzles each having a flow control valve openable in response to the directing of spray fluid at an operating pressure into each of said spray nozzles, the operating pressure of one of said spray nozzles being greater than the operating pressure of the other of said spray nozzles, and means for supplying spray fluid to said spray nozzles at least at the greater of the operating pressures, said means including a pair of return lines and a pair of return valves individually controlling" the flow of spray fluid through said return lines, said return valves being of different capacities, whereby when one of said return valves is opened the pressure of the spray fluid drops below the operating pressure of said one spray nozzle but remains above the operating pressure of said other spray nozzle and when the other. of said return valves is opened, the spray fluid pressure drops below that of both of said spray nozzles.

19. A spray gun and spray fluid system assembly, said spray gun including a pair of separate nozzle assemblies, each of said nozzle assemblies comprising a nozzle body, said nozzle body having a cylinder and a needle valve seat disposed in axial alignment, a piston and needle valve member unit mounted in said nozzle body and cooperating with said cylinder and said needle valve seat, respectively, a resilient member seated in said cylinder and bearing against said piston to normally urge said needle valve member into engagement with said needle valve seat, said nozzle body having a spray fluid inlet passage opening into said cylinder intermediate said piston and said needle valve seat, whereby said needle valve member is unseated by pressure of spray fluid on said piston, means connecting said nozzle assemblies to a common pressurized spray fluid source, and the pressure required to overcome the force of said resilient member of one of said spray nozzles being greater than the pressure required to overcome the force of the resilient member of the other of said spray nozzles whereby said other spray nozzle and both of said spray nozzles may be selectively operated, and means for supplying spray fluid to said spray gun at least at the pressure required to operate both of said nozzle assemblies, said means including a pair of return lines and a pair of return valves individually controlling the flow of spray fluid through said return lines, said return valves being of different capacities, whereby when one of said return valves is opened the pressure of the spray fluid drops below the operating pressure of one of said nozzle assemblies but remains above the operating pressure of the other of said nozzle assemblies and when the other of said return valves is opened the spray fluid pressure drops below that of both of said nozzle assemblies.

20. A rotating spray gun for spraying the interior of a can, said spray gun having an axis of rotation and ineluding a spray nozzle extending along said axis of rotation, said spray nozzle having a spray orifice offset from said :axis of rotation and opening generally endwise of said spray nozzle towards and at an angle to said axis of rotation for spraying the interior of a can body and an inner surface of a can end, a mounting block telescoped over said spray nozzle, and other spray nozzles pnojecting endwise from said mounting block in diametrically opposite relation, each of said other spray nozzles having a spray orifice opening generally parallel to said axis of rotation for spraying the interior of a can at the intersection between the can body and the can end.

References Cited in the file of this patent UNITED STATES PATENTS 1,258,322 Doellinger Mar. 5, 1918 2,013,431 Bechtold Sept. 3, 1935 2,053,312 Amery Sept. 8, 1936 2,565,543 Arvintz et a1. Apr. 28, 1951 2,759,763 Juvinall Aug'. 21, 1956 2,846,973 OOallaghan Aug. 12, 1958 2,888,903 Faber June 2, 1959 FOREIGN PATENTS 275,703 Switzerland June 15, 1951 1,011,885 France Apr. 9', 1952 

1. IN A PRESSURE OPERATED SPRAY GUN, A NOZZLE ASSEMBLY COMPRISING A NOZZLE BODY, A NOZZLE ORIFICE IN ONE END OF SAID NOZZLE BODY, SAID NOZZLE BODY HAVING A CYLINDER AND A NEEDLE VALVE SEAT DISPOSED IN AXIAL ALIGNMENT AND IN COMMUNICATION WITH SAID NOZZLE ORIFICE, A PISTON AND NEEDLE VALVE MEMBER UNIT MOUNTED IN SAID NOZZLE BODY AND COOPERATING WITH SAID CYLINDER AND SAID NEEDLE VALVE SEAT, RESPECTIVELY, FOR CONTROLLING THE FLOW OF SPRAY FLUID TO SAID NOZZLE ORIFICE, A RESILIENT MEMBER SEATED IN SAID CYLINDER AND BEARING AGAINST SAID PISTON TO NORMALLY URGE SAID NEEDLE VALVE MEMBER INTO ENGAGEMENT WITH SAID NEEDLE VALVE SEAT, SAID NOZZLE BODY HAVING A SPRAY FLUID INLET PASSAGE OPENING INTO SAID CYLINDER INTERMEDIATE SAID PISTON AND SAID NEEDLE VALVE SEAT, WHEREBY SAID NEEDLE VALVE MEMBER IS UNSEATED BY THE PRESSURE OF SPRAY FLUID ON SAID PISTON WHEN THE SPRAY FLUID PRESSURE IS AT THE OPERATING PRESSURE OF THE NOZZLE ASSEMBLY TO SUPPLY SPRAY FLUID TO SAID NOZZLE ORIFICE, MEANS CONNECTED TO SAID NOZZLE BODY FOR ROTATING SAID NOZZLE ASSEMBLY, AND SAID NOZZLE ORIFICE HAVING AN AXIS DISPOSED IN ANGULAR RELATION TO THE AXIS OF ROTATION AND OFFSET RELATIVE THERETO TO PROVIDE A MOVING SPRAY PATTERN. 